Optical character reader

Abstract

The invention provides an optical character reader (OCR) utilizing prioritized horizontal OR ranges for enhanced accuracy and ease of use. A light source illuminates a price tag or the like on which characters have been imprinted generally along a horizontal direction of the sheet. A lens system images the characters onto an image sensor having a field of vision covering a plurality of characters, the image sensor including a plurality of photo-electric conversion elements arranged in a matrix. A binary coding circuit digitizes outputs of the photo-electric conversion elements, which define picture elements (pixels), of an image in the field of vision of the image sensor, into binary signals representing black and white picture elements. A hand holdable scanner incorporates the light source, image sensor, lens system and binary coding circuit. An identifying circuit identifies characters from binary-coded data. The OCR utilizes at least two horizontal OR ranges in the field of vision of the image sensor. When the horizontal OR range of higher priority detects a character line, the result of character line detection is output. When none of the horizontal OR ranges detects a character line, it is determined that there is no character line. The character line detecting operation of each of the horizontal OR ranges is the same as that in the conventional OCR. However, in the OCR according to the present invention, the horizontal OR ranges are spread horizontally. Therefore, even in the case of a price tag which is long enough to have characters arranged along one of its sides, the character line or lines can be positively detected. Since at least two horizontal OR ranges are provided in the field of vision of the image sensor, therefore the pattern of the background of the price tag and the characters on the price tag can be distinguished from each other. This means that the OCR can be used for relatively small in size price tags. The OCR conserves electric power when it is not actively "reading" data by suspending its character identifying operations when not needed. Lines having no characters are identified and, in response, character identifying operations are stopped.

We claim: 
     
       1. An optical character reader (OCR) comprising: a light source for illuminating a sheet on which characters, which may include alpha-numeric characters and symbols, are arranged generally along a horizontal direction of said sheet;   an image sensor having a field of vision covering a plurality of said characters, said image sensor including a plurality of photo-electric conversion elements arranged in a matrix;   a lens system for receiving light reflected from said sheet, to form an image of said characters on said image sensor;   a binary coding circuit for digitalizing outputs of said photo-electric conversion elements, which define picture elements (pixels), of an image in the field of vision of said image sensor, into binary signals representing black and white picture elements;   a hand holdable scanner incorporating said light source, image sensor, lens system and binary coding circuit;   an identifying circuit for identifying characters from binary-coded data, wherein a plurality of prioritized horizontal OR ranges, each defined by two vertical lines are provided in the filed of vision of said image sensor;   a horizontal OR circuit for performing a horizontal OR operation providing an output "1" when, in said horizontal OR ranges at least one of said picture elements arranged in a horizontal direction is a black picture element, and providing an output "0" when said picture elements are all white picture elements, said horizontal OR circuit being provided for each or all of said horizontal OR ranges;   a black position/width detecting section for receiving an output of said horizontal OR circuit, to determine that a character line present when the total width of picture element lines in a vertical direction, which is the result of horizontal OR operations of which said output is "1", is within a predetermined range, said black position/width detecting section being provided for each of said horizontal OR ranges, and wherein with respect to all of said horizontal OR ranges, the presence or absence of a character line is detected; and   means for selecting a highest priority OR range from said plurality of prioritized OR ranges that contain character lines as determined by said black position width detecting section to determine the position of a character line or lines on said sheet.   
     
     
       2. An OCR according to claim 1, wherein a first horizontal OR range and a second horizontal OR range smaller in width than said first horizontal OR range are provided at the center of the field of vision of said image sensor in such a manner that said first and second horizontal OR ranges are laid one on another, and said first horizontal OR range is higher in the order of priority than said second horizontal OR range. 
     
     
       3. An OCR according to claim 1, wherein three horizontal OR ranges are provided at the center, left and right regions of the field of vision of said image sensor, respectively, in such a manner that said three horizontal OR ranges are spaced apart from one another, and said horizontal OR range at the center region is the first in the order of priority, said horizontal OR range at the left region is the second, and the said horizontal OR range at the right region is the third. 
     
     
       4. An optical character reader according to claim 1 wherein three horizontal OR ranges are provided at the center, right and left regions of the field of vision of said image sensor, respectively in such a manner that said three horizontal OR ranges are spaced from one another, and said horizontal OR range at the center region is the first in the order of priority, said horizontal OR ranges at the right region is the second, and said horizontal OR range at the left region is the third. 
     
     
       5. An optical character reader (OCR) comprising: a light source for illuminating a sheet on which characters, which may include alpha-numeric characters and symbols, are arranged generally along a horizontal direction of said sheet;   an image sensor having a field of vision covering a plurality of said characters, said image sensor including a plurality of photo-electric conversion elements arranged in a matrix;   a lens system for receiving light reflected from said sheet, to form an image of said characters on said image sensor;   a binary coding circuit for digitalizing outputs of said photo-electric conversion elements, which define picture elements (pixels), of an image in the field of vision of said image sensor, into binary signals representing black and which picture elements;   a hand holdable scanner incorporating said light source, image sensor, lens system and binary coding circuit;   an identifying circuit for identifying characters from binary-coded data, wherein a plurality of horizontal OR ranges, each defined by two vertical lines are provided in the field of vision of said image sensor;   a horizontal OR circuit for performing a horizontal OR operation that provides an output "1" when, in said horizontal OR ranges at least one of said picture elements arranged in a horizontal direction is a black picture element, and provides an output "0" when said picture elements are all white picture elements, said horizontal OR circuit being provided for each or all of said horizontal OR ranges;   a black position/width detecting section for receiving an output of said horizontal OR circuit, to determine that a character line is present when the total width of picture element lines in a vertical direction, which is the result of horizontal OR operations of which said output is "1", is within a predetermined range, said black position/width detecting section being provided for each of said horizontal OR ranges, and wherein with respect to all of said horizontal OR ranges, the presence or absence of a character line is detected; and   means for adding or selecting horizontal OR ranges from said plurality of horizontal OR ranges that contain character lines as determined by said black position/width detecting section to determine the position of a character line or lines thereby to achieve character identification.   
     
     
       6. An OCR according to claim 5 wherein said adding means subject said results of character line detection to addition to obtain a total character range in the field of vision when the results of character line detection of said plurality of horizontal OR ranges coincide in position with one another in the vertical direction. 
     
     
       7. An OCR according to claim 5 wherein said selecting means employs the result of character line detection whose position is higher in the vertical direction as a total character range in the field of vision when the results of character line detection of said plurality of horizontal OR ranges do not coincide in position with one another in the vertical direction. 
     
     
       8. An OCR according to claim 5 wherein said selecting means employs said results of character line detection that are lower in said vertical direction to obtain a total character range in the field of vision when the results of character line detection of said plurality of horizontal OR ranges do not coincide in position with one another in the vertical direction. 
     
     
       9. An OCR according to claim 5 wherein said selecting means employs said results of character line detection that are closer to the center in said vertical direction to obtain a total character range in the field of vision when the results of character line detection of said plurality of horizontal OR ranges do not coincide in position with one another in the vertical direction.